configure IP aliases on AIX

Navigate in smit:
Communications Applications and Services
 TCP/IP
  Further Configuration
   Network Interfaces
    Network Interface Selection
     Configure Aliases

OR
smit inetalias

chdev -l 'en1' -a alias4=x.x.x.x,y.y.y.y

where x.x.x.x is the address and y.y.y.y is the netmask